Micro led device and method of manufacturing the same

ABSTRACT

A micro light emitting diode (LED) device and a method of manufacturing the same are provided. A micro LED device includes a light emitting layer that is provided on a support substrate, a bonding layer, and a driver layer. The light emitting layer includes a stacked structure including a first semiconductor layer, an active layer, and a second semiconductor layer; first and second electrodes provided on a first side and a second side of the stacked structure; and a plurality of light emitting regions. The bonding layer is positioned between the support substrate and the light emitting layer. The drive layer includes a drive element electrically connected to the light emitting layer and is positioned on the light emitting layer to apply power to the plurality of light emitting regions of the light emitting layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Application No. 16/922,147,filed Jul. 7, 2020, which claims priority from Korean Patent ApplicationNo. 10-2019-0131387, filed on Oct. 22, 2019, in the Korean IntellectualProperty Office, the disclosure of which is herein incorporated byreference in its entirety.

BACKGROUND 1. Field

Example embodiments relate to a micro light emitting diode (LED) deviceand a method of manufacturing the same.

2. Description of Related Art

A liquid crystal display (LCD), an organic light emitting diode (OLED)display, and the like are widely used as a display device. Recently, atechnology for manufacturing a high-resolution micro light emittingdiode (LED) display by using a micro LED has received much attention.The LED has advantages of low power consumption and environmentalfriendliness. Thus, there is a high industrial demand for the LED.

It is necessary for a large-area substrate to be used as an epitaxialsubstrate for improving process yield when epitaxy of a Group III-VGaN-based micro LED is performed to manufacture a micro LED display. Inaddition, since the process is not easily performed due to a thickness,a weight, etc. of the large-area substrate when using the large-areasubstrate, an LED process is performed after a thickness of an epitaxialsubstrate is reduced to approximately half through a thin wafer process.

When the thickness of the epitaxial substrate is reduced toapproximately half so as to be advantageous in a fabrication process,compressive and tensile stress may greatly increase during a thin filmprocess, a breakage of the epitaxial substrate may occur due to a damagethat occurs during a handling process of the fabrication process, and/ordue to a strain during deposition and etching processes of an LEDprocess.

Accordingly, there is a need for a method of manufacturing a micro LEDdevice that is robust to a breakage and may be highly efficient.

SUMMARY

One or more example embodiments provide a micro light emitting diode(LED) device and a method of manufacturing the same which are robust toa breakage and highly efficient.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments of the disclosure.

According to an aspect of an example embodiment, provided is a microlight emitting diode (LED) device, including: a support substrate; alight emitting layer provided on the support substrate, the lightemitting layer including: a stacked structure including a firstsemiconductor layer, an active layer, and a second semiconductor layer;a first electrode and a second electrode provided on a first side and asecond side of the stacked structure, respectively; and a plurality oflight emitting regions; a bonding layer between the support substrateand the light emitting layer; and a drive layer provided on the lightemitting layer and including a drive element, the drive element beingelectrically connected to the light emitting layer and configured toapply power to the plurality of light emitting regions of the lightemitting layer.

The light emitting layer may further include an isolation structure thatseparates the plurality of light emitting regions from each other.

The drive element of the drive layer may include a thin film transistorconfigured to apply the power to the plurality of light emittingregions.

The drive element may include an n-MOS low-temperature polycrystallinesilicon (LPTS) thin film transistor.

The micro LED device may include a current blocking layer in a regioncorresponding to the isolation structure on the light emitting layer.

The micro LED device may include: a color conversion layer including aplurality of color conversion regions for converting a light emittedfrom the light emitting layer into light colors.

The color conversion layer may include a partition wall provided betweenthe plurality of color conversion regions.

The first electrode may be provided between the bonding layer and thefirst semiconductor layer; the second electrode may be a pixel electrodeand provided between the second semiconductor layer and the drive layer;and each of the plurality of light emitting regions may correspond to apixel, and a unit pixel may include two or more light emitting regions.

The unit pixel may include a first light emitting region, a second lightemitting region, and a third light emitting region of the light emittinglayer, and the plurality of color conversion regions may include: afirst color conversion region for converting a light generated in thefirst light emitting region into a first color light; a second colorconversion region for converting a light generated in the second lightemitting region into a second color light; and a third color conversionregion for converting a light generated in the third light emittingregion into a third color light.

The unit pixel may include a first light emitting region, a second lightemitting region, and a third light emitting region of the light emittinglayer, and the plurality of color conversion regions may include: afirst color conversion region for converting a light generated in thefirst light emitting region into a first color light; a second colorconversion region for converting a light generated in the second lightemitting region into a second color light; and a transparent region viawhich a light generated in the third light emitting region passeswithout color conversion.

According to an aspect of an example embodiment, provided is a method ofmanufacturing a micro light emitting diode (LED) device, the methodincluding: forming a stacked structure including a first semiconductorlayer, an active layer, and a second semiconductor layer of a lightemitting layer on a growth substrate in an order of the secondsemiconductor layer, the active layer, and the first semiconductorlayer; forming an isolation structure in the stacked structure to form aplurality of light emitting regions in the light emitting layer; forminga first electrode on the stacked structure; bonding a support substrateto the growth substrate, the support substrate facing the firstelectrode; removing the growth substrate and performing etching toremove a part of a thickness of the second semiconductor layer andexpose an end portion of the isolation structure; forming a secondelectrode electrically connected to the stacked structure and configuredto generate a light in the plurality of light emitting regions; andforming a drive layer including a drive element, the drive element beingelectrically connected to the second electrode on the light emittinglayer and configured to apply power to the plurality of light emittingregions.

The method of manufacturing the micro LED device may further include,prior to forming the second electrode, forming a current blocking layeron a region corresponding to the isolation structure, and the secondelectrode may be electrically connected to an upper surface of thestacked structure on which the current blocking layer is formed,corresponding to each light emitting region.

The isolation structure may be formed to a partial thickness of thesecond semiconductor layer, and the etching may be performed until atleast the end portion of the isolation structure is exposed by removingthe partial thickness of the second semiconductor layer.

The isolation structure may be formed by injecting ions.

The method of manufacturing the micro LED device may further include:forming a color conversion layer on the drive layer, the colorconversion layer including a plurality of color conversion regions forconverting a light emitted from the light emitting layer into lightcolors.

The color conversion layer may be formed to further include a partitionwall between the plurality of color conversion regions.

The first electrode may be a common electrode, and the second electrodemay be a pixel electrode; each of the plurality of light emittingregions may correspond to a pixel; and a unit pixel may include two ormore light emitting regions.

The unit pixel may include a first light emitting region, a second lightemitting region, and a third light emitting region of the light emittinglayer, and the plurality of color conversion regions may include: afirst color conversion region for converting a light generated in thefirst light emitting region into a first color light; a second colorconversion region for converting a light generated in the second lightemitting region into a second color light; and a third color conversionregion for converting a light generated in the third light emittingregion into a third color light.

The unit pixel may include a first light emitting region, a second lightemitting region, and a third light emitting region of the light emittinglayer, and the plurality of color conversion regions may include: afirst color conversion region for converting a light generated in thefirst light emitting region into a first color light; a second colorconversion region for converting a light generated in the second lightemitting region into a second color light; and a transparent region viawhich a light generated in the third light emitting region pass withoutcolor conversion.

The drive element of the drive layer may include an n-MOSlow-temperature polycrystalline silicon (LPTS) thin film transistorconfigured to apply the power to the plurality of light emittingregions.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIGS. 1 and 2 schematically illustrate a micro light emitting diode(LED) device according to example embodiments;

FIGS. 3 and 4 are cross-sectional views schematically illustrating microLED devices according to other example embodiments;

FIGS. 5 to 14 illustrate processes for manufacturing the micro LEDdevices according to example embodiments.

FIG. 15 schematically illustrates an n-type pixel circuit when a driveelement is implemented as an n-type thin film transistor by applyingmicro LED devices according to example embodiments;

FIG. 16 is a comparative example schematically illustrating a p-typepixel circuit when a drive element is implemented as a p-type thin filmtransistor in a micro LED device according to an example embodiment; and

FIG. 17 illustrates transfer characteristics of an n-channel thin filmtransistor and a p-channel thin film transistor.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the exampleembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, exampleembodiments are merely described below, by referring to the figures, toexplain aspects. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. Expressionssuch as “at least one of,” when preceding a list of elements, modify theentire list of elements and do not modify the individual elements of thelist.

Hereinafter, example embodiments will be described in detail withreference to the accompanying drawings. In the drawings, like referencenumerals refer to like elements, and a size of each element in thedrawings may be exaggerated for clarity and convenience of description.Example embodiments to be described below are merely examples, andvarious modifications are possible from example embodiments.

Hereinafter, what is described as “over” or “on” may include not onlydirectly over and in contact but also over without being in contact. Theterms first, second, and the like may be used to describe variousconfiguration elements, but are only used to distinguish oneconfiguration element from another configuration element. These terms donot limit the materials or structures of the configuration elements. Asingular expression includes plural expressions unless the contextclearly indicates otherwise. In addition, when a part is described to“include” a certain configuration element, which means that the part mayfurther include other configuration elements, except to exclude otherconfiguration elements unless otherwise stated. A term “above-described”and similar terminology may be used for the singular and the plural.

FIGS. 1 and 2 schematically illustrate a micro light emitting diode(LED) device 100 according to example embodiments. The micro LED device100 of FIG. 2 further includes a color conversion layer 150 as comparedwith FIG. 1 .

Referring to FIGS. 1 and 2 , the micro LED device 100 may include asupport substrate 110, a light emitting layer 140 on the supportsubstrate 110, and a drive layer 130 provided on the light emittinglayer 140. A bonding layer 120 may be formed between the supportsubstrate 110 and the light emitting layer 140. The color conversionlayer 150 may be further provided on the drive layer 130 to implement acolor. Here, the micro LED device 100 may be additionally oralternatively provided with a color filter separately for implementingthe color, instead of the color conversion layer 150.

The support substrate 110 may be a separate substrate from a growthsubstrate, for example, an epitaxial substrate, in which a stackedstructure of the light emitting layer 140 is formed through asemiconductor deposition process. The support substrate 110 may not bethe growth substrate. For example, a silicon substrate, a glasssubstrate, a sapphire substrate, a silicon substrate coated with SiO₂,or the like may be used as the support substrate 110. However, thesesubstrates are merely examples, and various other materials may be usedas the support substrate 110.

The bonding layer 120 may be formed between the support substrate 110and the light emitting layer 140. The bonding layer 120 may be a layerformed by bonding the light emitting layer 140 to the support substrate110 and may be a layer formed through, for example, adhesive bonding,eutectic bonding, or direct bonding. For example, an epoxy resin or aresin such as a silicone group, benzocyclobutene (BCB), a polysilazanegroup, or a siloxane group may be used for the adhesive bonding. Inaddition, the adhesive bonding may be performed by using a spin on glass(SOG) method. The eutectic bonding may use a metal. The direct bondingmay be performed by, for example, plasma, ion beam processing, etc. Thebonding layer 120 may be used to physically bond the light emittinglayer 140 to the support substrate 110, and thus, the light emittinglayer 140 may be bonded to the support substrate 110 by using a bondingmethod without an electrical connection.

The light emitting layer 140 may include a stacked structure of a firstsemiconductor layer 143, an active layer 144 located on the firstsemiconductor layer 143, and a second semiconductor layer 145 located onthe active layer 144. The light emitting layer 140 may include a firstelectrode 141 below the first semiconductor layer 143, and a secondelectrode 147 over the second semiconductor layer 145. In addition, thelight emitting layer 140 may further include an isolation structure 142to form a plurality of light emitting regions in the stacked structure.By including the isolation structure 142 for isolating the lightemitting regions from each other to form the plurality of light emittingregions as described above, a micro LED array may be formed. When theisolation structure 142 is formed such that each light emitting regioncorresponds to a pixel, the micro LED device 100 according to an exampleembodiment may be implemented as a micro LED display.

In the light emitting layer 140, the first semiconductor layer 143 mayinclude a first type semiconductor. For example, the first semiconductorlayer 143 may include a p-type semiconductor. The first semiconductorlayer 143 may include a Group III-V-based p-type semiconductor such asp-GaN. The first semiconductor layer 143 may have a single layerstructure or a multilayer structure.

The active layer 144 may generate light while electrons and holes arecombined. The active layer 144 may have a multi-quantum well (MQW)structure or a single-quantum well (SQW) structure. The active layer 144may include a Group III-V-based semiconductor such as GaN.

The second semiconductor layer 145 may include, for example, an undopedsemiconductor, that is, a u-type semiconductor or an n-type dopedsemiconductor, that is, an n-type semiconductor. The secondsemiconductor layer 145 may include a Group III-V-based u-typesemiconductor such as u-GaN or an n-type semiconductor such as n-GaN.The second semiconductor layer 145 may have a single layer structure ora multilayer structure.

The stacked structure of the first semiconductor layer 143, the activelayer 144, and the second semiconductor layer 145 of the light emittinglayer 140 may be grown through, for example, a GaN-based semiconductordeposition process.

As described above, the light emitting layer 140 may have the isolationstructure 142 such that light from the active layer 144 is emitted in aunit of each light emitting region. That is, the light emitting layer140 may have the isolation structure 142 between adjacent light emittingregions. When the micro LED device 100 according to an exampleembodiment is implemented as a micro LED display, the light emittingregions may respectively correspond to pixels.

For example, the light emitting layer 140 may have the isolationstructure 142 such that light from the active layer 144 is emitted inunits of pixels. A unit pixel may include two or more light emittingregions to enable color implementation. When each light emitting regioncorresponds to a pixel, the unit pixel may include, for example, threepixels or four pixels to enable the color implementation.

The isolation structure 142 may be, for example, an ion injectionregion. Here, ions may include, for example, nitrogen (N) ions, boron(B) ions, argon (Ar) ions, or phosphorus (P) ions. Since no currentflows into the ion injection region, light may not emit therefrom. Whenthe isolation structure 142 is formed as the ion injection region, amicro LED array structure may be implemented without an etching processof the light emitting layer 140 for the isolation structure 142.

The first electrode 141 and the second electrode 147 may be provided atboth sides of the stacked structure of the light emitting layer 140. Thefirst electrode 141 may be located between the bonding layer 120 and thefirst semiconductor layer 143 and may be formed to be electricallyconnected to, for example, the first semiconductor layer 143. The secondelectrode 147 may be located between the second semiconductor layer 145and the drive layer 130 and may be formed to be electrically connectedto, for example, the second semiconductor layer 145. The first electrode141 may be a common electrode, and the second electrode 147 may be apixel electrode. When the first semiconductor layer 143 includes ap-type semiconductor, the first electrode 141 may be a common electrodeand a p-type electrode. That is, the first electrode 141 may be a p-typecommon electrode. The second electrode 147 may be, for example, ann-type electrode.

The first electrode 141 may include a reflective material to reflectlight, emitted from the active layer 144 toward a lower portion of theactive layer 144. The first electrode 141 may be formed of an electrodematerial including, for example, Ag, Au, Al, Cr, Ni, Ti, an alloythereof, etc. and may be formed to have a single-layer structure or amultilayer structure. For example, the first electrode 141 may have amultilayer structure of Ti/Al/Ti.

The second electrode 147 may be formed as a transparent electrode or anopaque electrode. The transparent electrode may include, for example,indium tin oxide (ITO), ZnO, indium zinc oxide (IZO), IGZO, etc. Whenthe second electrode 147 is formed as a transparent electrode, thesecond electrode 147 may be disposed to entirely cover the secondsemiconductor layer 145. When the second electrode 147 is an opaqueelectrode, the second electrode 147 may further include a window region149 to transmit light emitted from the active layer 144. For example,the second electrode 147 may be formed of an electrode materialincluding Mo to have the window region 149.

A current blocking layer 146 may be further provided in a regioncorresponding to the isolation structure 142. When the current blockinglayer 146 is provided, the second electrode 147 may be formed on thecurrent blocking layer 146 to extend over a top surface of the secondsemiconductor layer 145.

The drive layer 130 may include a drive element 135 electricallyconnected to the light emitting layer 140 to apply power to each of theplurality of light emitting regions of the light emitting layer 140. Thedrive element 135 may be electrically connected to the second electrode147. The drive element 135 may include a thin film transistor to applypower to each of the plurality of light emitting regions. For example,the drive element 135 may include an n-MOS low-temperaturepolycrystalline silicon (LPTS) thin film transistor. In addition,various types of thin film transistors, for example, a high electronmobility transistor (HEMT), etc. may be used as the drive element 135.

Referring to FIG. 2 , the color conversion layer 150 provided on or overthe drive layer 130 may include a plurality of color conversion regions151, 153, and 155 for converting light emitted from the active layer 144into light colors. Based on the color conversion layer 150 including theplurality of color conversion regions 151, 153, and 155, the micro LEDdevice 100 according to an example embodiment may implement a colormicro LED display.

For example, the color conversion regions of the color conversion layer150 may respectively correspond to the light emitting regions of thelight emitting layer 140. When each of the light emitting regions of thelight emitting layer 140 corresponds to a pixel, and a unit pixelincludes two or more light emitting regions and two or more colorconversion regions corresponding, one to one, to the light emittingregions and converting light to different color each other such that aunit pixel enables color to be implemented, the micro LED device 100according to an example embodiment may be implemented as a color microLED display.

FIG. 2 illustrates an example case where a unit pixel includes a firstlight emitting region 140 a, a second light emitting region 140 b, and athird light emitting region 140 c of the light emitting layer 140, andthe first color conversion region 151, the second color conversionregion 153, and the third color conversion region 155 of the colorconversion layer 150 correspond, one to one, to the first to the thirdlight emitting regions 140 a, 140 b, and 140 c. The first colorconversion region 151 may convert the light generated in the first lightemitting region 140 a into first color light. The second colorconversion region 153 may convert the light generated in the secondlight emitting region 140 b into second color light. The third colorconversion region 155 may convert the light generated in the third lightemitting region 140 c into third color light.

For example, the active layer 144 of the light emitting layer 140 mayemit blue light. In this case, the first to the third light emittingregions 140 a, 140 b, and 140 c may generate blue light, and the firstto the third color conversion regions 151, 153, and 155 may convert theincident blue light into the first to the third color light. Forexample, the color conversion layer 150 may include a red conversionregion, a green conversion region, and a blue conversion region as thefirst to the third color conversion regions 151, 153, and 155,respectively. The red conversion region corresponds to a red pixel, thegreen conversion region corresponds to a green pixel, and the blueconversion region corresponds to a blue pixel. In an example embodiment,when the active layer 144 emits blue light, instead of providing a blueconversion region as the third color conversion region 155, atransparent region that makes the light generated in the third lightemitting region 140 c pass therethrough without color conversion may beprovided.

The first color conversion region 151, for example, the red conversionregion, may convert blue light emitted from the active layer 144 intored light and emit the red light. The red conversion region may include,for example, quantum dots (QDs) of a predetermined size that are excitedby blue light to emit red light. Also, the red conversion region mayinclude a phosphor which is excited by blue light B emitted from theactive layer 144 to emit red light. The red conversion region mayfurther include a photoresist or a light scattering agent.

The second color conversion region 153, for example, the greenconversion region, may convert light emitted from the active layer 144into green light and emit the green light. The green conversion regionmay include, for example, QDs of a predetermined size that are excitedby blue light to emit green light. Also, the green conversion region mayinclude a phosphor that is excited by light emitted from the activelayer 144 to emit green light. The green conversion region may furtherinclude a photoresist having good transmission characteristics or alight scattering agent that uniformly emits green light.

In the red conversion region and the green conversion region, the QDsmay have a core-shell structure including a core portion and a shellportion or may have a particle structure without a shell. The core-shellstructure may have a single shell or multi-shells. The multi-shells maybe, for example, double-shells. The QD may include, for example, atleast one of a Group II-VI-based semiconductor, a Group III-V-basedsemiconductor, a Group IV-based semiconductor, and graphene QDs. As anexample, the QD may include at least one of Cd, Se, Zn, S, and InP, andis not limited thereto. Each QD may have a diameter less than or equalto several tens of nm, for example, a diameter less than or equal toapproximately 10 nm.

The third color conversion region 155 may be a transparent region viawhich blue light emitted from the active layer 144 pass and is emittedto the outside. In an example embodiment, when the blue light is emittedfrom the active layer 144, the third color conversion region 155 may beprovided as a blue conversion region, and the blue conversion region mayinclude QDs of a predetermined size that are excited by, for example,the blue light to emit the blue light having a changed spectralbandwidth. In the blue conversion region, the QD may have a core-shellstructure including a core portion and a shell portion or may have aparticle structure without a shell. The core-shell structure may have asingle shell or multi-shells. The third color conversion region 155 mayfurther include a photoresist having good transmission characteristicsor a light scattering agent that uniformly emits the blue light.

FIG. 2 illustrates a case where a unit pixel includes three pixels, thatis, one red pixel, one green pixel, and one blue pixel, which is merelyan example and the example embodiments of the disclosure are not limitedthereto. For example, the micro LED device 100 according to an exampleembodiment implemented as a color micro LED display may include fourpixels, for example, one red pixel, two green pixels, and one bluepixel. In this case, the color pixels may be arranged in, for example, aBayer pattern.

In addition, the light emitted from the active layer 144 is not limitedto blue light and may be light having a different wavelength as long asthe light may excite the first to the third color conversion regions151, 153, and 155, and the first to the third color conversion regions151, 153, and 155 of the color conversion layer 150 may be provided toconvert incident light into red light, green light, and blue light,according to a wavelength of the light generated in the active layer144.

The color conversion layer 150 may further include a partition wall 157between the color conversion regions. A side surface of the partitionwall 157 may be formed as a reflective surface or may be configured by ablack matrix for absorbing light. The black matrix may improve contrastby preventing color crosstalk from occurring between color conversionregions.

In the above-described structure, for example, if the drive element 135corresponding to a red pixel is driven to apply a predetermined voltagebetween the first electrode 141 and the second electrode 147corresponding to the red pixel, blue light is emitted from the activelayer 144 of the first light emitting region 140 a located below the redcolor conversion region, that is, the first color conversion region 151,and the blue light emitted is converted into red light in the redconversion region to be emitted to the outside.

In addition, for example, if the drive element 135 corresponding to agreen pixel is driven and a predetermined voltage is applied between thefirst electrode 141, which is a common electrode, and the secondelectrode 147 corresponding to the green pixel, the blue light isemitted from the active layer 144 of the second light emitting region140 b located below the green conversion region 152, that is, the secondcolor conversion region 153, and the emitted blue light is incident onthe green conversion region to be converted into green light and emittedto the outside.

In addition, for example, if the drive element 135 corresponding to ablue pixel is driven to apply a predetermined voltage between the firstelectrode 141, which is the common electrode, and the second electrode147 corresponding to the blue pixel, for example, blue light is emittedfrom the active layer 144 located below the blue conversion region, thatis, the third color conversion region 155, and the blue light passingthrough the blue color conversion region is emitted to the outside.

FIGS. 3 and 4 are cross-sectional views schematically illustrating microLED devices 200 and 300 according to other example embodiments. Themicro LED device 300 of FIG. 4 further includes a color conversion layer350 as compared with the micro LED device 200 of FIG. 3 .

Referring to FIGS. 3 and 4 , the micro LED devices 200 and 300 mayinclude a support substrate 210, a light emitting layer 240 on thesupport substrate 210, and a drive layer 230 provided on the lightemitting layer 240. A bonding layer 220 may be formed between thesupport substrate 210 and the light emitting layer 240. In addition, thecolor conversion layer 350 may be further provided on the drive layer230 as illustrated in FIG. 4 .

The support substrate 210 may be a substrate separate from a growthsubstrate, for example, an epitaxial substrate, in which the lightemitting layer 240 and the drive layer 230 are formed through asemiconductor deposition process, etc. That is, the support substrate210 may not be the growth substrate. For example, a silicon substrate, aglass substrate, a sapphire substrate, a silicon substrate coated withSiO₂, or the like may be used as the support substrate 210. However,these substrates are merely examples and various other materials may beused for the support substrate 210.

The bonding layer 220 may be formed between the support substrate 210and the light emitting layer 240. The bonding layer 220 may be a layerformed by bonding the light emitting layer 240 to the support substrate210 and may be a layer formed through, for example, adhesive bonding,eutectic bonding, or direct bonding. For example, an epoxy resin or aresin such as a silicone group, benzocyclobutene (BCB), a polysilazanegroup or Siloxane may be used for the adhesive bonding. In addition, theadhesive bonding may be performed by using a SOG method. The eutecticbonding may use a metal. The direct bonding may be performed by, forexample, plasma, ion beam processing, etc. The bonding layer 220 is forphysically bonding the light emitting layer 240 to the support substrate210 and may bond the light emitting layer 240 to the support substrate210 by using a bonding method that does not require an electricalconnection.

The light emitting layer 240 may include a stacked structure of a firstsemiconductor layer 243, an active layer 244 located on the firstsemiconductor layer 243, and a second semiconductor layer 245 located onthe active layer 244. In addition, the light emitting layer 240 mayfurther include an isolation structure 242 to form a plurality of lightemitting regions 240 a, 240 b, and 240 c within the stacked structure.By providing the isolation structure 242 that separates the lightemitting regions from each other to form the plurality of light emittingregions 240 a, 240 b, and 240 c, a micro LED array may be formed. Whenthe isolation structure 242 is formed such that each light emittingregion corresponds to a pixel, the micro LED devices 200 and 300according to an example embodiment may be implemented as micro LEDdisplays.

In the light emitting layer 240, the first semiconductor layer 243 mayinclude a first type semiconductor. For example, the first semiconductorlayer 243 may include a p-type semiconductor. The first semiconductorlayer 243 may include a Group III-V-based p-type semiconductor such asp-GaN. The first semiconductor layer 243 may have a single layerstructure or a multilayer structure.

The active layer 244 may generate light while combining electrons andholes. The active layer 244 may have an MQW structure or an SQWstructure. The active layer 244 may include a Group III-V-basedsemiconductor such as GaN.

The second semiconductor layer 245 may include, for example, an undopedsemiconductor, that is, a u-type semiconductor or an n-type dopedsemiconductor, that is, an n-type semiconductor. The secondsemiconductor layer 245 may include a Group III-V-based u-typesemiconductor such as u-GaN or an n-type semiconductor such as n-GaN.The second semiconductor layer 245 may have a single layer structure ora multilayer structure. For example, a fine pattern structure (notillustrated) or the like may be further provided at a location close tothe drive layer 230 of the second semiconductor layer 245 to increaseefficiency of light generated in the active layer 244 and extractedthrough the second semiconductor layer 245.

As described above, the light emitting layer 240 may have the isolationstructure 242 such that light from the active layer 244 is emitted inunits of the light emitting regions 240 a, 240 b, and 240 c. That is,the light emitting layer 240 may have the isolation structure 242between adjacent light emitting regions. When the micro LED devices 200and 300 according to example embodiments are implemented as micro LEDdisplays, the light emitting regions 240 a, 240 b, and 240 c mayrespectively correspond to pixels.

For example, the light emitting layer 240 may have the isolationstructure 242 such that the light from the active layer 244 is emittedin units of pixels. Each of the light emitting regions 140 a, 140 b, and140 c may correspond to the pixel.

In this case, the unit pixel may include a single light emitting regionor may include two or more light emitting regions to enable colorimplementation.

When the color conversion layer 350 is not provided as illustrated inFIG. 3 , the unit pixel may include a single light emitting region or aplurality of light emitting regions. The color may be implemented bygenerating light of different colors from at least three light emittingregions among the plurality of light emitting regions belonging to theunit pixel, or by additionally disposing a color filter separately fromthe micro LED device 200.

When the color conversion layer 350 is further included as illustratedin FIG. 4 , the unit pixel may include, for example, three pixels orfour pixels to enable color implementation. In this case, the lightemitting layer 240 may be provided such that the plurality of lightemitting regions 240 a, 240 b and 240 c belonging to the unit pixelgenerate light having the same wavelength bandwidth. Here, even when thecolor conversion layer 350 is further provided, the light emitting layer240 may be provided such that at least three light emitting regions ofthe plurality of light emitting regions 240 a, 240 b, and 240 cbelonging to the unit pixel generate light having different wavelengthbandwidth.

FIGS. 3 and 4 illustrate an example case where the unit pixel has thethree light emitting regions 240 a, 240 b, and 240 c and a structurethereof. The micro LED array may have a two-dimensional array of theunit pixel.

The isolation structure 242 may be, for example, an ion injectionregion. Here, ions may include, for example, nitrogen (N) ions, boron(B) ions, argon (Ar) ions, phosphorus (P) ions, or the like. Since nocurrent flows into the ion injection region, light may not be emittedfrom the ion injection region. When the isolation structure 242 isformed as the ion injection region, the micro LED array structure may beimplemented without an etching process of the light emitting layer 240for the isolation structure 242.

A first electrode 241 and a second electrode 247 may be provided at bothsides of the stacked structure of the light emitting layer 240. Thefirst electrode 241 may be located between the bonding layer 220 and thefirst semiconductor layer 243 and may be formed to be electricallyconnected to, for example, the first semiconductor layer 243. The secondelectrode 247 may be located between the second semiconductor layer 245and the drive layer 230 and may be formed to be electrically connectedto, for example, the second semiconductor layer 245. The first electrode241 may be a common electrode, and the second electrode 247 may be apixel electrode. When the first semiconductor layer 243 includes ap-type semiconductor, the first electrode 241 may be the commonelectrode and may be a p-type electrode. That is, the first electrode241 may be a p-type common electrode. The second electrode 247 may be,for example, an n-type electrode.

The first electrode 241 may include a reflective material to reflectlight emitted from the active layer 244 toward a lower portion of theactive layer 244. The first electrode 241 may be formed of an electrodematerial including, for example, Ag, Au, Al, Cr, Ni, Ti, an alloythereof, or the like, and may have a single layer structure or amultilayer structure. For example, the first electrode 241 may be formedto have a multilayer structure of Ti/Al/Ti.

The second electrode 247 may be formed as a transparent electrode or anopaque electrode. The transparent electrode may include, for example,indium tin oxide (ITO), ZnO, indium zinc oxide (IZO), IGZO, or the like.When the second electrode 247 is formed as the transparent electrode,the second electrode 247 may be disposed to entirely cover the secondsemiconductor layer 245. When the second electrode 247 is an opaqueelectrode, the second electrode 247 may further include a window region249 such that light emitted from the active layer 244 passestherethrough. For example, the second electrode 247 may be formed of anelectrode material including Mo to have the window region 249.

A current blocking layer 246 may be further provided on a regioncorresponding to the isolation structure 242. The current blocking layer246 may be formed of, for example, silicon oxide. The current blockinglayer 246 may prevent a current from leaking to an adjacent lightemitting region. The current blocking layer 246 may be provided betweena top surface of the isolation structure 242 and the second electrode247. When the current blocking layer 246 is provided, the secondelectrode 247 may be formed on the current blocking layer 246 to extendover the top surface of the second semiconductor layer 245.

An insulating layer 237 may be further provided between the drive layer230 and the light emitting layer 240. A via hole 238 may be furtherprovided in the insulating layer 237 to electrically connect a driveelement 235 to the second electrode 247.

The drive layer 230 may include the drive element 235 electricallyconnected to each of the light emitting regions 240 a, 240 b, and 240 cof the light emitting layer 240 such that power is applied to each ofthe plurality of light emitting regions 240 a, 240 b, and 240 c of thelight emitting layer 240. The drive element 235 may be electricallyconnected to the second electrode 247 through the via hole 238. Thedrive element 235 may include a thin film transistor such that power isapplied to each of the light emitting regions 240 a, 240 b, and 240 c.For example, the drive element 235 may include an n-MOS low-temperaturepolycrystalline silicon (LPTS) thin film transistor. For example, in thedrive element 235, an active layer may include low-temperaturepolycrystalline silicon to form an n-MOS low-temperature polycrystallinesilicon (LPTS) thin film transistor. In addition to this, various typesof thin film transistors, for example, a high electron mobilitytransistor (HEMT) and the like may be applied to the drive element 235.The drive layer 230 may further include at least one of insulatinglayers 231, 232. The insulating layer 232 may be, for example, a gateoxide.

The drive layer 230 and the drive element 235 illustrated in FIGS. 3 and4 are merely examples, and the drive layer 230 and the drive element 235applied to the micro LED devices 200 and 300 according to the exampleembodiments may have various structures.

Referring to FIG. 4 , the color conversion layer 350 provided on or overthe drive layer 230 may include a plurality of color conversion regions351, 353, and 355 for converting the light emitted from the active layer244 into light colors. By further providing the color conversion layer350 including the plurality of color conversion regions 351, 353, and355, the micro LED device 300 according to an example embodiment mayimplement a color micro LED display.

For example, the color conversion regions of the color conversion layer350 may respectively correspond to the light emitting regions of thelight emitting layer 240. When each of the light emitting regions of thelight emitting layer 240 corresponds to a pixel, and a unit pixelincludes two or more light emitting regions and two or more colorconversion regions corresponding, one to one, to the light emittingregions and converting light to different color each other such that aunit pixel enables color to be implemented, the micro LED device 300according to an example embodiment may be implemented as a color microLED display.

FIGS. 3 and 4 illustrate an example case where a unit pixel includesfirst to third light emitting regions 240 a, 240 b, and 240 c of thelight emitting layer 240, and first to third color conversion regions351, 353, and 355 of the color conversion layer 350 correspond, one toone, to the first to the third light emitting regions 240 a, 240 b, and240 c. In this case, the first color conversion region 351 may convertthe light generated in the first light emitting region 240 a into firstcolor light. The second color conversion region 353 may convert thelight generated in the second light emitting region 240 b into secondcolor light. The third color conversion region 355 may convert the lightgenerated in the third emission region 240 c into third color light.

For example, the active layer 244 of the light emitting layer 240 mayemit blue light. In this case, the blue light is generated in the first,second, and third light emitting regions 240 a, 240 b, and 240 c, andthe first, second, and third color conversion regions 351, 353, and 355may convert the incident blue light into first to third color light. Thecolor conversion layer 350 may include a red conversion region, a greenconversion region, and a blue conversion region as the first to thethird color conversion regions 351, 353, and 355. The red conversionregion corresponds to a red pixel, the green conversion regioncorresponds to a green pixel, and the blue conversion region maycorrespond to a blue pixel. In an example embodiment, when the activelayer 244 emits blue light, instead of providing a blue conversionregion as the third color conversion region 355, a transparent regionthat makes the light generated in the third light emitting region 240 cpass therethrough without color conversion may be provided.

That is, it is considered that a case where, when the active layer 244of the light emitting layer 240 emits blue light and the unit pixelincludes the red pixel, the green pixel, and the blue pixel, the unitpixel includes the first to the third light emitting regions 240 a, 240b, and 240 c of the light emitting layer 240, and the color conversionlayer 350 includes the first to the third color conversion regions 351,353, and 355. In this case, the first color conversion region 351 of thecolor conversion layer 350 may be formed as a red conversion region thatconverts the blue light generated in the first light emitting region 240a into first color light, for example, red light. The second colorconversion region 353 of the color conversion layer 350 may be formed asa green conversion region that converts the blue light generated in thesecond light emitting region 240 b into second color light, for example,green light. The third color conversion region 355 of the colorconversion layer 350 may be formed as a blue conversion region thatconverts the blue light generated in the third light emitting region 240c into blue light having a changed spectral range, or may be atransparent region that makes light pass therethrough without colorconversion.

As described above, the first color conversion region 351, for example,the red conversion region may change the blue light emitted from theactive layer 244 into red light and emit the red light. The redconversion region may include, for example, QDs of a predetermined sizethat are excited by the blue light and emit red light. In addition, thered conversion region may include a phosphor which is excited by theblue light emitted from the active layer 244 and emits the red light.The red conversion region may further include a photoresist or a lightscattering agent.

The second color conversion region 353, for example, a green conversionregion may the light emitted from the active layer 244 into green lightand emit the green light. The green conversion region may include, forexample, QDs of a predetermined size that are excited by the blue lightand emit green light. In addition, the green conversion region may alsoinclude a phosphor that is excited by the light emitted from the activelayer 244 and emits the green light. The green conversion region mayfurther include a photoresist having good transmission characteristicsor a light scattering agent that uniformly emits green light.

In the red conversion region and the green conversion region, the QDsmay have a core-shell structure including a core portion and a shellportion or may have a particle structure without a shell. The core-shellstructure may have a single shell or multi-shells. The multi-shells maybe, for example, double-shells. The QD may include, for example, atleast one of a Group II-VI-based semiconductor, a group III-V-basedsemiconductor, a Group IV-based semiconductor, and graphene QDs. As anexample, the QD may include at least one of Cd, Se, Zn, S, and InP, andis not limited thereto. Each QD may have a diameter less than or equalto several tens of nm, for example, a diameter less than or equal toapproximately 10 nm.

The third color conversion region 355 may be a transparent region viawhich blue light emitted from the active layer 244 pass and is emittedto the outside. In addition, when the blue light is emitted from theactive layer 244, the third color conversion region 355 may be providedas a blue conversion region, and at this time, the blue conversionregion may include QDs of a predetermined size that are excited by, forexample, the blue light to emit the blue light having a changed spectralbandwidth. In the blue conversion region, the QD may have a core-shellstructure including a core portion and a shell portion or may have aparticle structure without a shell. The core-shell structure may have asingle shell or multi-shells. The third color conversion region 355 mayfurther include a photoresist having good transmission characteristicsor a light scattering agent that uniformly emits the blue light.

FIGS. 3 and 4 illustrate a case where a unit pixel includes threepixels, that is, one red pixel, one green pixel, and one blue pixel,which is merely an example and the example embodiments of the disclosureare not limited thereto. For example, the micro LED device 300 and 400according to example embodiments implemented as a color micro LEDdisplay may include four pixels, for example, one red pixel, two greenpixels, and one blue pixel. In this case, the color pixels may bearranged in, for example, a Bayer pattern.

In addition, the light emitted from the active layer 244 is not limitedto blue light and may be light having a different wavelength as long asthe light may excite the first to the third color conversion regions351, 353, and 355, and the first to the third color conversion regions351, 353, and 355 of the color conversion layer 350 may be provided toconvert incident light into color light for color display, for example,red light, green light, and blue light, according to a wavelength of thelight generated in the active layer 244.

The color conversion layer 350 may further include partition walls 357between the color conversion regions 351, 353, and 355 adjacent to eachother. A side surface of the partition wall 357 may be formed as areflective surface, thereby, increasing extraction efficiency of colorlight converted in each color conversion regions 351, 353, and 355 to beoutput. In addition, the partition wall 357 may be configured with ablack matrix for absorbing light. The black matrix may improve contrastby preventing color crosstalk between the color conversion regions.

In the above-described structure, for example, if the drive element 235corresponding to the red pixel is driven to apply a predeterminedvoltage between the first electrode 241 and the second electrode 247corresponding to the red pixel, blue light is emitted from the activelayer 244 of the first light emitting region 240 a located below the redcolor conversion region, that is, the first color conversion region 351,and the blue light emitted is converted into red light in the firstcolor conversion region 351 to be emitted to the outside.

In addition, for example, if the drive element 235 corresponding to agreen pixel is driven and a predetermined voltage is applied between thefirst electrode 241 which is a common electrode and the second electrode247 corresponding to the green pixel, the blue light is emitted from theactive layer 244 of the second light emitting region 240 b located belowthe green conversion region 352, that is, the second color conversionregion 353, and the emitted blue light is incident on the second colorconversion region 353 to be converted into green light and emitted tothe outside.

In addition, for example, if the drive element 235 corresponding to theblue pixel is driven to apply a predetermined voltage between the firstelectrode 241 which is the common electrode and the second electrode 247corresponding to the blue pixel, for example, blue light is emitted fromthe active layer 244 located below the blue conversion region, that is,the third color conversion region 355, and the blue light passes throughthe third color conversion region to be emitted to the outside.

Since the micro LED device 200 and 300 according to example embodimentshave a structure including a light emitting layer 240 on the supportsubstrate 210 and the drive layer 230 on the light emitting layer 240,the light emitting layer 240 may be bonded to the support substrate 210in a state where a semiconductor stacked structure of the light emittinglayer 240 is grown on a growth substrate, and the growth substrate maybe removed, and then, a process of manufacturing the drive element 235of the drive layer 230 or a subsequent process of manufacturing thecolor conversion layer 350 may be performed.

In a process of manufacturing the micro LED devices 100, 200, and 300according to example embodiments, a GaN-based semiconductor stackedstructure of the light emitting layer 240 may be grown on the growthsubstrate through a relatively high temperature process. In addition, asubsequent process may be performed in a state where the light emittinglayer 240 is bonded to the support substrate 210 through a bondingprocess.

Sapphire, silicon, etc. are mainly used as the growth substrate used forepitaxy of a Group III-V GaN-based LED, and a large-area substrate isused for improving yield of a process. A GaN-based micro LED may bemanufactured based on a large-area silicon substrate, and when thesilicon substrate is used, there is an advantage in implementing thedrive circuit. When a GaN-based LED is manufactured in the large-areasilicon substrates, for example, a silicon wafer having a thickness ofapproximately 1 to 2 mm, which is hundred times, for example, about 150times through about 250 times a thickness (within an approximately 7 µmGaN-based semiconductor layer), is required to be used, in considerationof stress applied due to a high-temperature growth of metal organicchemical vapor deposition (MOCVD).

In order to implement the micro LED devices 100, 200, and 300 accordingto example embodiments as micro LED displays, a relatively thick andheavy growth substrate may be used for a large-area process.

Therefore, even when the micro LED devices 100, 200, and 300 accordingto example embodiments are manufactured, a silicon wafer having athickness of approximately 1 to 2 mm, for example, approximately 1.5 mmmay be used as a growth substrate in consideration of stress generatedin a high-temperature growth of a GaN-based light emitting layersemiconductor stacked structure.

For example, a silicon substrate having a first thickness such as athickness of approximately 1.5 mm may be used as a growth substrate suchthat the micro LED devices 100, 200, and 300 according to exampleembodiments may be manufactured in a large-area process.

A process of manufacturing is not easily performed due to a thicknessand a weight of a growth substrate for the large-area process.

Therefore, a subsequent process is generally performed in a state wherea semiconductor stacked structure of a light emitting layer is formed inthe growth substrate and a thickness of the growth substrate is reducedthrough a thin wafer process.

That is, the thin wafer process is performed after a semiconductorstacked structure of an LED requiring a high-temperature growth isformed in a silicon substrate having a first thickness such as athickness of approximately 1.5 mm. The thickness of the siliconsubstrate having the first thickness is reduced by approximately half tobecome a second thickness such as a thickness of approximately 0.75 mmthrough the thin wafer process, and a fabrication processes such as anetching process, a lithography process, and a metal deposition processis performed to form an LED structure for the thinned growth substrate.

When the micro LED device is manufactured by applying the thin waferprocess, the thickness of the growth substrate is reduced toapproximately half in a state where the GaN-based LED semiconductorstacked structure is formed in the growth substrate, a fabrication(Fab.) process for an LED structure and a p-MOS element process forforming a thin film transistor which is a drive element are performed, asupport substrate is bonded to the thinned growth substrate, theremaining growth substrate is removed secondly, and the rest of theprocess is performed.

Here, the thinned growth substrate is advantageous in a manufacturingprocess, while compressive and/or tensile stress is greatly increasedduring a thin film process, and thus, a breakage of the thinned growthsubstrate may occur due to a damage in a handling process during themanufacturing process, and/or a damage due to a strain may occur duringdeposition/etching of a process of manufacturing the micro LED device.In addition, a thin wafer process is first performed for the growthsubstrate, a process of completely removing the thinned growth substratebonded to the support substrate is additionally performed. Accordingly,removing the growth substrate is performed twice, and thus, it isdifficult to simplify the manufacturing process.

However, the micro LED devices 100, 200, and 300 of example embodimentshave a structure in which the light emitting layer 240 is bonded ontothe support substrate 210 and the drive layer 230 is located on thelight emitting layer 240, and thus, a semiconductor stacked structure ofthe light emitting layer 240 requiring a high-temperature growth isformed based on the growth substrate, the growth substrate is completelyremoved in a state where the light emitting layer 240 is bonded to thesupport substrate, and thereafter a subsequent process such as a processof forming the drive layer 230 and a process of forming the colorconversion layer 350 may be performed. An n-MOS element process isperformed in a low temperature process to form a thin film transistorwhich is the drive element 235 of the drive layer 230.

Therefore, according to the micro LED devices 100, 200, and 300 ofexample embodiments, since a subsequent process may be performed after agrowth substrate is completely removed in a single process, processstress is reduced such that the possibility of a substrate breakage issignificantly reduced, and a process tact time is reduced tosignificantly reduce the possibility of an in-process breakage. Also,since a subsequent process is performed after a mechanical strengthincreases due to bonding of a support substrate, a micro LED deviceaccording to example embodiments may be robust to a breakage.

In addition, according to the micro LED devices 100, 200, and 300 ofexample embodiments, since an n-type thin film transistor is applied tothe drive element 235 of the drive layer 230, mobility thereof issuperior to mobility of a p-type thin film transistor, resulting inreducing a width to length ratio (e.g., width/length (W/L)) of a drivethin film transistor at the same pixel current, and thereby, a pixelsper inch (PPI) pixel circuit may be easily implemented.

Therefore, according to the micro LED devices 100, 200, and 300 ofexample embodiments, a high-resolution micro LED device robust to abreakage may be implemented.

Hereinafter, processes for manufacturing the micro LED devices accordingto example embodiments will be described in detail with reference toFIGS. 5 to 14 . FIGS. 5 to 14 illustrate example processes formanufacturing the micro LED devices 200 and 300 of FIGS. 3 and 4 and maybe applied to manufacturing the micro LED device 100 of FIGS. 1 and 2 .Substantially the same configuration elements are denoted by the samereference numerals, and repetitive description may be omitted.

In order to manufacture the micro LED devices 200 and 300 according toexample embodiments, a stacked structure of the second semiconductorlayer 245, the active layer 244, and the first semiconductor layer 243for the light emitting layer 240 is grown on a growth substrate 201, asillustrated in FIG. 5 . For example, a silicon substrate or a sapphiresubstrate may be used as the growth substrate 201.

The second semiconductor layer 245 may be formed of, for example, anundoped semiconductor, that is, a u-type semiconductor or an n-typedoped semiconductor, that is, an n-type semiconductor. The secondsemiconductor layer 245 may include a Group III-V-based u-typesemiconductor such as u-GaN or an n-type semiconductor such as n-GaN.The second semiconductor layer 245 may have a single layer structure ora multilayer structure.

The active layer 244 may be formed to have an MQW structure or an SQWstructure to generate light while electrons combine with holes. Theactive layer 244 may include a Group III-V-based semiconductor such asGaN.

The first semiconductor layer 243 may be formed of a first typesemiconductor. For example, the first semiconductor layer 243 may beformed of a p-type semiconductor. The first semiconductor layer 243 mayinclude a Group III-V-based p-type semiconductor such as p-GaN. Thefirst semiconductor layer 243 may have a single layer structure or amultilayer structure.

For example, a stacked structure of the second semiconductor layer 245,the active layer 244, and the first semiconductor layer 243 for thelight emitting layer 240 may be formed by growing GaN on a siliconsubstrate having a thickness of approximately 1.5 mm. For example, theGaN stacked structure of the light emitting layer 240 may be configuredwith u-GaN, MQW, and p-GaN, and a thickness thereof may be formed to beless than or equal to approximately 7 µm.

Next, as illustrated in FIG. 6 , in order to form the isolationstructure 242 such that the light from the active layer 244 of the lightemitting layer 240 is emitted in units of each of the light emittingregions 240 a, 240 b, and 240 c, an ion injection process may beperformed. Here, ions may include, for example, nitrogen (N) ions, boron(B) ions, argon (Ar) ions, phosphorus (P) ions, etc. Since no currentflows into the ion injection region, light may not be emitted from theion injection region. Therefore, by forming the isolation structure 242by using the ion injection process, the light emitting regions 240 a,240 b, and 240 c may be formed to respectively correspond to pixels. Ioninjection for forming the isolation structure 242 may be performed to apredetermined depth (e.g., a partial depth) of the second semiconductorlayer 245.

When the isolation structure 242 is formed as an ion injection region,the micro LED array structure may be implemented without an etchingprocess of the light emitting layer 240 for the isolation structure 242.In addition, through a process for forming the isolation structure 242,the light from the active layer 244 of the light emitting layer 240 maybe emitted in units of pixels, and each of the light emitting regions140 a, 140 b, and 140 c may correspond to the pixel. The unit pixel mayinclude a single light emitting region or may include two or more lightemitting regions to enable color implementation.

Next, as illustrated in FIG. 7 , the first electrode 241 may be formedon the first semiconductor layer 243. The first electrode 241 may be acommon electrode or a p-type electrode. The first electrode 241 may beformed on or over the entirety of the stacked structure of the lightemitting layer 240. The first electrode 241 may include a reflectivematerial to reflect light emitted from the active layer 244 toward thefirst electrode 241. For example, the first electrode 241 may be formedof an electrode material including, for example, Ag, Au, Al, Cr, Ni, Ti,an alloy thereof, etc. and may be formed to have a single layerstructure or a multilayer structure. For example, the first electrode241 may have a multilayer structure of Ti/Al/Ti.

Next, as illustrated in FIG. 8 , the growth substrate 201 is turnedupside down such that the first electrode 241 of the growth substrate201 faces the support substrate 210, and in this state, the lightemitting layer 240 is bonded to the support substrate 210. The bondinglayer 220 may be formed between the support substrate 210 and the firstelectrode 241 of the growth substrate 201.

The support substrate 210 is a substrate different from a growthsubstrate in which the light emitting layer 240 is formed through asemiconductor deposition process, for example, an epitaxial substrate,and for example, a silicon substrate, a glass substrate, a sapphiresubstrate, a silicon substrate coated with SiO₂, or the like may be usedas the support substrate. However, these substrates are merely examples,and various other materials may be used as the support substrate 210.

The bonding layer 220 may be a layer formed by bonding the lightemitting layer 240 to the support substrate 210 and may be a layerformed through, for example, adhesive bonding, eutectic bonding, ordirect bonding. For example, an epoxy resin or a resin such as asilicone group, benzocyclobutene (BCB), a polysilazane group, or asiloxane group may be used for the adhesive bonding. In addition, theadhesive bonding may be performed by using a SOG method. The eutecticbonding may use a metal. The direct bonding may be performed by, forexample, plasma, ion beam processing, etc. The bonding layer 220 may beused to physically bond the light emitting layer 240 to the supportsubstrate 210, and thus, the light emitting layer 140 may be bonded tothe support substrate 110 by using a bonding method without anelectrical connection.

FIG. 8 illustrates that the bonding layer 220 is formed on the supportsubstrate 210, but this is merely an example and the bonding layer 220may be formed on the light emitting layer 240 or may be formed duringthe bonding process.

Next, as illustrated in FIG. 9 , the growth substrate 201 on the lightemitting layer 240 may be removed to expose the second semiconductorlayer 245.

Subsequently, an etching process may be performed on the entire surfaceof the second semiconductor layer 245 as illustrated in FIG. 10 . Byremoving a part of a thickness of the second semiconductor layer 245through the etching process, the second semiconductor layer 245 may havea desirable thickness such as a thickness of approximately 500 nm. Forexample, the second semiconductor layer 245 may be a GaN layer and maybe etched to have a thickness less than or equal to approximately 500nm.

The process of removing a partial thickness of the second semiconductorlayer 245 may be performed until at least an end portion of theisolation structure 242 is exposed. Here, the etching process may alsobe performed until a partial thickness of the isolation structure 242 isremoved.

As described above, a plurality of light emitting regions 240 a, 240 b,and 240 c may be formed by exposing the end portion of the isolationstructure 242 to partition the light emitting layer 240 by the isolationstructure 242. The light emitting layer 240 may have the isolationstructure 242 between adjacent light emitting regions. When the microLED devices 200 and 300 according to example embodiments are implementedas micro LED displays, the light emitting regions 240 a, 240 b, and 240c may respectively correspond to pixels. The unit pixel may include aplurality of light emitting regions, for example, three light emittingregions 240 a, 240 b, and 240 c, or four or more light emitting regions,and the micro LED devices 200 and 300 according to example embodimentsmay have a two-dimensional array of the unit pixel.

Next, as illustrated in FIG. 11 , the current blocking layer 246 may beformed on a region corresponding to the isolation structure 242. Thecurrent blocking layer 246 may be formed of, for example, silicon oxide.The current blocking layer 246 may prevent a current from leaking to theadjacent light emitting region.

Next, as illustrated in FIG. 12 , the second electrode 247 may be formedon the current blocking layer 246 to extend over the top surface of thesecond semiconductor layer 245. The second electrode 247 may be, forexample, an n-type electrode.

The second electrode 247 may be formed as a transparent electrode or anopaque electrode. The transparent electrode may include, for example,indium tin oxide (ITO), ZnO, indium zinc oxide (IZO), IGZO, etc. Whenthe second electrode 247 is formed as the transparent electrode, thesecond electrode 247 may be disposed to entirely cover the secondsemiconductor layer 245. When the second electrode 247 is an opaqueelectrode, the second electrode 247 may further include the windowregion 249 to make the light emitted from the active layer 244 passtherethrough. FIG. 12 illustrates an example in which the secondelectrode 247 is formed to have the window region 249. For example, thesecond electrode 247 may be formed of an electrode material including Moto have the window region 249.

For example, a fine pattern structure (not illustrated) or the like maybe further formed on an upper surface of or near the secondsemiconductor layer 245 to increase efficiency of the light generated bythe active layer 244 and extracted through the second semiconductorlayer 245. The fine pattern structure may be formed after the secondelectrode 247 is formed or may be formed before the second electrode 247is formed or before the current blocking layer 246 is formed.

Next, as illustrated in FIG. 13 , the insulating layer 237 may be formedon the light emitting layer 240, and the drive layer 230 including thedrive element 235 may be formed on the insulating layer 237. The viahole 238 may be further formed in the insulating layer 237 toelectrically connect the drive element 235 to the second electrode 247.

The drive layer 230 may include the drive element 235 electricallyconnected to each of the light emitting regions 240 a, 240 b, and 240 cof the light emitting layer 240 such that power is applied to each ofthe plurality of light emitting regions 240 a, 240 b, and 240 c of thelight emitting layer 240. The drive element 235 may be electricallyconnected to the second electrode 247 through the via hole 238.

The drive element 235 may include a thin film transistor such that thepower is applied to each of the plurality of light emitting regions 240a, 240 b, and 240 c. For example, the drive element 235 may be formed ofan n-MOS low-temperature polycrystalline silicon (LPTS) thin filmtransistor. For example, an active layer of the drive element 235 mayinclude low-temperature polycrystalline silicon to form an n-MOSlow-temperature polycrystalline silicon (LPTS) thin film transistor. Inaddition, the drive element 235 may include various types of thin filmtransistors, for example, a high electron mobility transistor (HEMT) andthe like. The drive layer 230 may further include at least one ofinsulating layer 231, 232, and the insulating layer 232 may include, forexample, a gate oxide.

By forming the drive layer 230 in this manner, the micro LED device 200may be obtained.

Additionally, as illustrated in FIG. 14 , the color conversion layer 350including the plurality of color conversion regions 351, 353, and 355for converting light emitted from the active layer 244 into light colorsmay be further provided on or over the drive layer 230. By furtherproviding the color conversion layer 350 including the plurality ofcolor conversion regions 351, 353, and 355, the micro LED device 300according to an example embodiment may be obtained to implement a colormicro LED display.

The color conversion regions of the color conversion layer 350 mayrespectively correspond to light emitting regions of the light emittinglayer 240.

For example, a unit pixel may include the first to the third lightemitting regions 240 a, 240 b, and 240 c of the light emitting layer240, and the first to the third color conversion regions 351, 353, and355 of the color conversion layer 350 may respectively correspond to thefirst to the third light emitting regions 240 a, 240 b, and 240 c. Thefirst color conversion region 351 may convert the light generated in thefirst light emitting region 240 a, for example, blue light into a firstcolor light, for example, red light. The second color conversion region353 may convert the light generated in the second light emitting region240 b, for example, blue light into a second color light, for example,red light. The third color conversion region 355 may convert the lightgenerated in the third light emitting region 240 c, for example, bluelight into a third color light or to make the light pass therethroughwithout color conversion.

The first to the third color conversion regions 351, 353, and 355 of thecolor conversion layer 350 may be respectively a red conversion region,a green conversion region, and a blue conversion region, and mayrespectively correspond to a red pixel, a green pixel, and a blue pixel

The first color conversion region 351, for example, the red conversionregion may be formed to include QDs of a predetermined size or phosphorsthat are excited by blue light to emit red light. In addition, the redconversion region may further include a photoresist having goodtransmission characteristics or a light scattering agent that uniformlyemits red light.

The second color conversion region 353, for example, the greenconversion region may be formed to include QDs of a predetermined sizeor phosphors that are excited by the blue light to emit green light. Thegreen conversion region may further include a photoresist having goodtransmission characteristics or a light scattering agent that uniformlyemits green light.

The third color conversion region 355 may be provided as a transparentregion or a blue conversion region that makes blue light emitted fromthe active layer 244 pass therethrough and emits the blue light to theoutside. At this time, the blue conversion region may include, forexample, QDs of a predetermined size or phosphors that are excited bythe blue light to emit blue light having a changed spectral bandwidth.The blue conversion region may further include a photoresist having goodtransmission characteristics or a light scattering agent that uniformlyemits the blue light.

The color conversion layer 350 may be formed to further include thepartition wall 357 between the color conversion regions 351, 353, and355 adjacent to each other. A side surface of the partition wall 357 maybe formed as a reflective surface or may be configured by a black matrixfor absorbing light.

In the micro LED devices 200 and 300 described above, for example, whenthe drive element 235 corresponding to the red pixel is driven to applya predetermined voltage between the first electrode 241 and the secondelectrode 247 corresponding to the red pixel, blue light is emitted fromthe active layer 244 of the first light emitting region 240 a locatedbelow the red color conversion region, that is, the first colorconversion region 351, and the blue light emitted is converted into redlight in the first color conversion region 351 to be emitted to theoutside.

In addition, for example, when the drive element 235 corresponding to agreen pixel is driven and a predetermined voltage is applied between thefirst electrode 241 which is a common electrode and the second electrode247 corresponding to the green pixel, the blue light is emitted from theactive layer 244 of the second light emitting region 240 b located belowthe green conversion region, that is, the second color conversion region353, and the emitted blue light is incident on the second colorconversion region 353 to be converted into green light and emitted tothe outside.

In addition, for example, when the drive element 235 corresponding tothe blue pixel is driven to apply a predetermined voltage between thefirst electrode 241 which is the common electrode and the secondelectrode 247 corresponding to the blue pixel, for example, blue lightis emitted from the active layer 244 located below the blue conversionregion, that is, the third color conversion region 355, and the bluelight passes through the third color conversion region to be emitted tothe outside.

The process of manufacturing the micro LED devices 200 and 300 describedabove with reference to FIGS. 5 to 14 may be applied to the process ofmanufacturing the micro LED device 100 of FIGS. 1 and 2 in the samemanner.

According to the micro LED devices 100, 200, and 300 of exampleembodiments described above, since a subsequent process may be performedafter a growth substrate is completely removed in a single process,process stress is reduced such that the possibility of a substratebreakage is significantly reduced, and a process tact time is reduced tosignificantly reduce the possibility of an in-process breakage. Also,since a subsequent process is performed after a mechanical strengthincreases due to bonding of a support substrate, a micro LED deviceaccording to example embodiments may be robust to a breakage.

In addition, according to the micro LED devices 100, 200, and 300 ofexample embodiments, since an n-type thin film transistor is applied tothe drive element 235 of the drive layer 230, mobility thereof issuperior to mobility of a p-type thin film transistor, resulting inreducing a width/length (W/L) of a drive thin film transistor at thesame pixel current, and thereby, a PPI pixel circuit may be easilyimplemented.

FIG. 15 schematically illustrates an n-type pixel circuit when the driveelement 235 is implemented as an n-type thin film transistor by applyingthe micro LED devices 100, 200, and 300 according to exampleembodiments. FIG. 16 is a comparative example schematically illustratinga p-type pixel circuit when the drive element is implemented as a p-typethin film transistor in the micro LED device. FIG. 17 illustratestransfer characteristics of an n-channel thin film transistor and ap-channel thin film transistor.

As can be seen from the transfer characteristics of FIG. 17 , as in FIG.15 , when the micro LED devices 100, 200, and 300 according to anexample embodiment are applied to implement an n-type pixel circuit,mobility thereof may be superior to mobility of a p-type pixel circuitto which the micro LED device of the comparative example of FIG. 16 isapplied. Therefore, according to the PPI pixel circuit to which themicro LED devices 100, 200, and 300 according to an example embodimentare applied, the width/length (W/L) of the drive thin film transistor(TFT) can be reduced at the same pixel current, thereby implementing ahigh PPI pixel further easier.

As described above, according to the micro LED devices 100, 200, and 300of example embodiments, since an n-type thin film transistor is appliedthereto, mobility thereof is superior to mobility of a p-type thin filmtransistor, resulting in reducing a width/length (W/L) of a drive thinfilm transistor at the same pixel current, and thereby, a PPI pixelcircuit is easily implemented, resulting in enabling a high-resolutionmicro LED device robust to a breakage.

Although the above-described micro LED device 100, 200, and 300, and amethod of manufacturing the same are described with reference to exampleembodiments illustrated in the drawings, these are merely illustrative,and those skilled in the art should understand that variousmodifications and other equivalent embodiments are possible. While manydetails are set forth in the foregoing description, those should beconstrued as illustrations of example embodiments rather than to limitthe scope of the disclosure. Therefore, the scope of the disclosureshould not be determined by the described embodiments.

According to the micro LED devices of example embodiments, a structureis provided in which a light emitting layer is formed on a supportsubstrate and a drive layer is formed on the light emitting layer, thelight emitting layer may be bonded to the support substrate in a statewhere a semiconductor stacked structure of the light emitting layerrequiring a high-temperature process is grown on a growth substrate, andthe growth substrate may be removed, and then, a process ofmanufacturing a drive element of the drive layer or a subsequent processof manufacturing a color conversion layer may be performed, and thus, aprocess tact time is reduced to significantly reduce the possibility ofan in-process breakage. Also, since a subsequent process is performedafter a mechanical strength increases due to bonding of a supportsubstrate, a micro LED device robust to a breakage may be implementedaccording to an example embodiment. In addition, according to an exampleembodiment, since an n-type thin film transistor is applied to a driveelement of a drive layer, mobility thereof is superior to mobility of ap-type thin film transistor, resulting in reducing a width/length (W/L)of a drive thin film transistor at the same pixel current, and thereby,a PPI pixel circuit may be easily implemented, resulting in implementinga high-resolution micro LED device robust to a breakage.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments. While one or more embodiments have beendescribed with reference to the figures, it will be understood by thoseof ordinary skill in the art that various changes in form and detailsmay be made therein without departing from the spirit and scope asdefined by the following claims.

What is claimed is:
 1. A micro light emitting diode (LED) display,comprising: a support substrate; a light emitting layer provided on thesupport substrate, the light emitting layer comprising: a stackedstructure including a first semiconductor layer, an active layer, and asecond semiconductor layer; a first electrode and a second electrodeprovided on a first side and a second side of the stacked structure,respectively; and a plurality of light emitting regions eachcorresponding a pixel; a bonding layer between the support substrate andthe light emitting layer; a drive layer provided on the light emittinglayer and comprising a drive element, the drive element beingelectrically connected to the light emitting layer and configured toapply power to the plurality of light emitting regions of the lightemitting layer; and a color conversion layer including a plurality ofcolor conversion regions for converting a light emitted from the lightemitting layer into light colors, wherein the support substrate is aseparate substrate from a growth substrate on which the stackedstructure of the light emitting layer is formed through a semiconductordeposition process, and the bonding layer is formed between the supportsubstrate and the light emitting layer by bonding the support substrateto the growth substrate.
 2. The micro LED display of claim 1, whereinthe light emitting layer further comprises an isolation structure thatseparates the plurality of light emitting regions from each other. 3.The micro LED display of claim 2, wherein the drive element of the drivelayer comprises a thin film transistor configured to apply the power tothe plurality of light emitting regions.
 4. The micro LED display ofclaim 3, wherein the drive element comprises an n-MOS low-temperaturepolycrystalline silicon (LPTS) thin film transistor.
 5. The micro LEDdisplay of claim 2, further comprising: a current blocking layer in aregion corresponding to the isolation structure on the light emittinglayer.
 6. The micro LED display of claim 1, wherein the color conversionlayer further comprises a partition wall provided between the pluralityof color conversion regions.
 7. The micro LED display of claim 1,wherein the first electrode is provided between the bonding layer andthe first semiconductor layer, wherein the second electrode is a pixelelectrode and provided between the second semiconductor layer and thedrive layer, and wherein a unit pixel includes two or more lightemitting regions.
 8. The micro LED display of claim 7, wherein the unitpixel comprises a first light emitting region, a second light emittingregion, and a third light emitting region of the light emitting layer,and wherein the plurality of color conversion regions comprise: a firstcolor conversion region for converting a light generated in the firstlight emitting region into a first color light; a second colorconversion region for converting a light generated in the second lightemitting region into a second color light; and a third color conversionregion for converting a light generated in the third light emittingregion into a third color light.
 9. The micro LED display of claim 7,wherein the unit pixel comprises a first light emitting region, a secondlight emitting region, and a third light emitting region of the lightemitting layer, and wherein the plurality of color conversion regionscomprise: a first color conversion region for converting a lightgenerated in the first light emitting region into a first color light; asecond color conversion region for converting a light generated in thesecond light emitting region into a second color light; and atransparent region via which a light generated in the third lightemitting region passes without color conversion.
 10. A method ofmanufacturing a micro light emitting diode (LED)display, the methodcomprising: forming a stacked structure including a first semiconductorlayer, an active layer, and a second semiconductor layer of a lightemitting layer on a growth substrate in an order of the secondsemiconductor layer, the active layer, and the first semiconductorlayer; forming an isolation structure in the stacked structure to form aplurality of light emitting regions each corresponding the a pixel inthe light emitting layer; forming a first electrode on the stackedstructure; bonding a support substrate to the growth substrate, thesupport substrate facing the first electrode; removing the growthsubstrate and performing etching to remove a part of a thickness of thesecond semiconductor layer and expose an end portion of the isolationstructure; forming a second electrode electrically connected to thestacked structure and configured to generate a light in the plurality oflight emitting regions; forming a drive layer including a drive element,the drive element being electrically connected to the second electrodeon the light emitting layer and configured to apply power to theplurality of light emitting regions; and forming a color conversionlayer on the drive layer, the color conversion layer including aplurality of color conversion regions for converting a light emittedfrom the light emitting layer into light colors.
 11. The method ofmanufacturing the micro LED display of claim 10, further comprising,prior to forming the second electrode, forming a current blocking layeron a region corresponding to the isolation structure, wherein the secondelectrode is electrically connected to an upper surface of the stackedstructure on which the current blocking layer is formed, correspondingto each light emitting region.
 12. The method of manufacturing the microLED display of claim 10, wherein the isolation structure is formed to apartial thickness of the second semiconductor layer, and wherein theetching is performed until at least the end portion of the isolationstructure is exposed by removing the partial thickness of the secondsemiconductor layer.
 13. The method of manufacturing the micro LEDdisplay of claim 12, wherein the isolation structure is formed byinjecting ions.
 14. The method of manufacturing the micro LED display ofclaim 10, wherein the color conversion layer is formed to furtherinclude a partition wall between the plurality of color conversionregions.
 15. The method of manufacturing the micro LED display of claim10, wherein the first electrode is a common electrode, and the secondelectrode is a pixel electrode, and wherein a unit pixel includes two ormore light emitting regions.
 16. The method of manufacturing the microLED display of claim 15, wherein the unit pixel comprises a first lightemitting region, a second light emitting region, and a third lightemitting region of the light emitting layer, and wherein the pluralityof color conversion regions comprise: a first color conversion regionfor converting a light generated in the first light emitting region intoa first color light; a second color conversion region for converting alight generated in the second light emitting region into a second colorlight; and a third color conversion region for converting a lightgenerated in the third light emitting region into a third color light.17. The method of manufacturing the micro LED display of claim 15,wherein the unit pixel comprises a first light emitting region, a secondlight emitting region, and a third light emitting region of the lightemitting layer, and wherein the plurality of color conversion regionscomprise: a first color conversion region for converting a lightgenerated in the first light emitting region into a first color light; asecond color conversion region for converting a light generated in thesecond light emitting region into a second color light; and atransparent region via which a light generated in the third lightemitting region passes without color conversion.
 18. The method ofmanufacturing the micro LED display of claim 10, wherein the driveelement of the drive layer comprises an n-MOS low-temperaturepolycrystalline silicon (LPTS) thin film transistor configured to applythe power to the plurality of light emitting regions.
 19. A micro lightemitting diode (LED) display, comprising: a support substrate; a lightemitting layer provided on the support substrate, the light emittinglayer comprising: a stacked structure including a first semiconductorlayer, an active layer, and a second semiconductor layer; a firstelectrode and a second electrode provided on a first side and a secondside of the stacked structure, respectively; and a plurality of lightemitting regions each corresponding the a pixel; a bonding layer betweenthe support substrate and the light emitting layer; a drive layerprovided on the light emitting layer and comprising a drive element, thedrive element being electrically connected to the light emitting layerand configured to apply power to the plurality of light emitting regionsof the light emitting layer; and a color filter disposed on the drivelayer for color implement, wherein the support substrate is a separatesubstrate from a growth substrate on which the stacked structure of thelight emitting layer is formed through a semiconductor depositionprocess, and the bonding layer is formed between the support substrateand the light emitting layer by bonding the support substrate to thegrowth substrate.
 20. The micro LED display of claim 19, wherein thelight emitting layer further comprises an isolation structure thatseparates the plurality of light emitting regions from each other; and,a current blocking layer in a region corresponding to the isolationstructure on the light emitting layer.